radio connection problems with 1998 laguna?

I RECENTLY TOOK OUT MY OLD PHILLIPS RADIO/CASSETTE,TO REPLACE IT WITH A RENAULT VDO TUNER LIST RADIO/CD PLAYER.
TWO OF THE WIRE CONNECTIONS FROM THE CAR FIT INTO THE BACK OF THE NEW CD PLAYER,BUT ONE IS A LONG CONNECTION THAT DOES NOT FIT INTO THE BACK OF NEW CD/RADIO.THE FITTING IS DIFFERENT SHAPE AT THE BACK OF THE NEW RADIO/CD PLAYER, BECAUSE OF THIS THE RADIO/CD PLAYER WILL NOT WORK?
ANYONE HAVE ANY IDEAS WHAT I NEED TO DO ? OR WHAT I NEED TO GET THE LAST CABLE TO FIT INTO BACK OF NEW RADIO/CD PLAYER
THANKS.